Chamber of secrets

The room isn’t much to look at – small and plain, with a twin bed, a chair, a dorm-size refrigerator, a sink and a toilet.

But the spartan appearance is deceiving.

This “metabolic chamber” at the UNC Nutrition Research Institute in Kannapolis, N.C., has cost about $1 million to build and maintain. It’s the newest and most sensitive of 17 such research tools in the world, according to its director, Dr. Steven Zeisel.

Scientists hope the chamber will help them unlock the secrets of human metabolism and provide answers for people who struggle to control their weight.

By monitoring volunteers who stay overnight in the 8- by 11-foot space, researchers will try to identify foods, activity levels and genes that affect human metabolism. With that, they’ll be able to prescribe customized diets and exercise plans that are more likely to work for specific people.

“Nowadays people jump around from diet to diet, and most of the time it doesn’t work. Then they get discouraged and maybe just give up,” says Karen Corbin, a dietitian and research fellow at the institute.

“But once you know for sure what’s going to work for someone, and they follow your recommendation and see a result, they’re going to be more motivated to stick to it.”

Earlier this year, researchers from UNC and Appalachian State published results from the first study using the metabolic chamber. It found that 10 men who exercised vigorously for 45 minutes in the morning continued to burn calories over the next 14 hours.

Proof that an “afterburn” exists could motivate people to exercise intensely enough to get the added benefit, Corbin says.

Currently, the chamber is being used to study whether black pepper increases metabolism. If it does, look for the sponsoring spice company to tout weight-loss-enhancing properties.

Institute researchers will work with other food companies and pharmaceutical manufacturers as they try to increase understanding of the role of diet and activity in normal brain development, cancer prevention and the treatment of obesity.

“Everyone’s trying to develop products that help people lose weight,” says Andrew Swick, director of obesity and eating disorders research at the institute.

“The ultimate goal is individualized nutrition,” he says. “We’d love to be able to tell people, ‘You’re more likely to lose weight by exercising.’ Or ‘You’re more likely to lose weight by eating this.’ We’d like to be able to make recommendations individually based on somebody’s genetics.”

So far, about 50 volunteers have spent time in the metabolic chamber.

On a recent day, a 50-something woman sat inside the soundproof space, watching a movie on a laptop computer. In an outer room, a computer displayed measurements of the amount oxygen she had consumed, carbon dioxide emitted and calories burned.

She is one of 18 postmenopausal women being monitored for the pepper study. Animal studies suggest that black pepper increases metabolism. Anecdotally, people get hot when they eat pepper, which could mean they burn more calories. But this is the first human study of the hypothesis, Swick says.

Research subjects stay in the chamber about 24 hours on two occasions, a week apart. During one stay, they eat food made with pepper. During the other stay, they eat food without pepper.

Although they eat the same foods, they get different amounts.

“Some people burn less calories per pound. Some people burn more calories per pound,” Swick explains. “We have to feed them an exact amount of calories based on their energy needs.”

For example, one woman required 1,550 calories while another needed 2,150.

In the institute’s “metabolic kitchen,” cooks prepare food to order, with the exact number of calories, proteins, carbohydrates and fats prescribed by researchers.

Meals are delivered to the chamber in a pass-through between double doors that prevent air from escaping. Subjects must eat their meals at specific times and finish in a certain amount of time.

They get up every hour to stretch, and they’re not allowed to sleep, except at nighttime, because that would decrease their metabolism and skew the study results.

At the end of the study, Swick says, “We’ll find out whether black pepper increases metabolic rate or not. … We’ll be able to detect less than a 100-calorie difference (per day).”

That’s a small amount, but it adds up over time.

“If you overeat by 100 calories per day, you would gain 10 pounds in a year,” says Swick. “If we can find three or four things that raise your calorie requirements and your energy expenditure by 50 to 100 calories (per day), that would be huge.”

Researchers at the institute and elsewhere are excited about the potential for finding answers to questions about metabolism.

“There’s a lot that we still need to learn about the factors that influence energy balance,” says Dr. Russ Pate, an exercise science professor and researcher at the University of South Carolina.

“What’s important about a metabolic chamber is that it enables you to study issues related to energy balance in a very precise way.”

Precision is important, he says, because “if you average it out, it’s really a tiny number of calories per day that ultimately results in excessive weight gain and obesity.”

“Telling everybody the same thing just doesn’t work,” adds Corbin, the dietitian. “There’s got to be a better way.”